Treatment of motor fuel



Patented Jim; 11,1940

UNITED STATES satan c PATENT o FlcE murmur or iro'roa anal. Jaeque o. 'Morrell, cmcazo, m.', assignor to Universal Oil ProductsCompany, Chicago, 111.,

a corporation of Delaware No mam. Application May 4, 193a.

Serial No; 205,985

9 claims; aa 196- 50) This application is a continuation-in-part of my co-pending application Serial No. 120,041, filed January 11,1937.

This invention relates particularly to the treat- 5 ment of motor fuels of low antiknock value, such as straight run gasolines produced from parafiinic crudes though the process is also. applicable for improving the knock rating of corresponding gasoline fractions of better antiknock characteris- 10 tics such as gasolines from naphthenic base crudesoccur and the yields of high knock rating product are higher. Further objects and advantages will become apparent in the description of the essential details of the process.

increase in its content of olefinic and cyclic (particularly aromatic) .compounds though this rule v cannot be stated as absolute since experiments on pure compounds have shown their knock rating is also a function of such factors as the length of the straight chain in the paraffin hydrocarbons, the position of the double bond in the corresponding olefins, the degree of partial or 35. complete saturation of the cyclic hydrocarbons and the presence ofminor amounts of substances which may exert an accelerating or a retarding influence upon the rate of combustion of the fuel. Therefore, while it may be stated generally that the antiknock value of a fuel is increased by loss of hydrogen incidental to the formation of ,olefins and cyclic hydrocarbons such as would occur in a reforming operation, other'reactions may also take place, the course of which is not so well known or so well defined, to witz'isomerizationvinvolving theformation of branched chain saturated and unsaturated hydrocarbons and the formation of hydrocarbons of a mixed straight chain andcyclic character.

In one specific embodiment the invention comprises the treatment of hydrocarbon motor fuels or fractions thereof in heated vaporous condition at temperatures and for periods of time under which relatively little cracking would occur in the absence of catalysts, in the presence of catalysts comprising modified felds'pars which have been treated for the removal of a substantial portion of their alkali metal and aluminum content and then caused to adsorb minor amounts of promoters from metal salt solutions.

-As a general rule the antiknock value of a hydrocarbon motor fuel mixture increases with w It has been found that when using catalyticcontact materials of the above character, the

reforming process is essentially one of dehydrogenation (the gas formed is chracterized by rel atively high content of hydrogen) and may be cafried out at temperatures ranging from a minimum at which noticeable dehydrogenation occurs up to a maximum corresponding to excessive gas formation.

hydrogenation. The present catalytic process is to be differentiated from ordinary noncatalyticreforming processes in the more specific char-- acter of the reactions which occur since their is relatively little cracking in the ordinary sense of the word in which large quantities of methane and other light hydrocarbon gases are formed, indicating splitting or rupture of the carbon chain.

'As a result of extended investigations it has been found that catalysts'of the character men'- tioned possess unusual value in reforming reactions. To assist in developing the character of ,the preferred-catalysts, the. following brief description of the feldspars as a mineral-group is given:

The feldspars are ortho silicates of alkali and/or alkaline earth metals and aluminum, the

alkali and alkaline earth metals being in isomorphous mixtures. Thegeneral formula 'forthe feldspar minerals is: (R,R')A1Sla0a, in which R represents an alkali metal, usually sodium .or potassium, and R represents an-alkalineearth metal, usually calcium or barium, since the feldspars are quite uniformly characterized by the complete absence of magnesium and iron. '3 and B. may be considered collectively under the term alkalinous metal. The following table gives the names and formulas of the principal minerals of the feldspar group, these being taken from "A System of Mineralogy, by Dana, 6th edition, page 314'.

.Fnnnsraa Gaour camasiaoc' At the higher temperatures the reaction is no longer substantially de- 7 I The general characteristics of the feldspar minerals are their crystallization in the monoclinic or triclinic systems; their cleavage in two similar directions at'an angle of about 90; their hardness, falling between 6 and'6.5; their specific gravity, falling principally betweenf2.55 and 2.75,

and'their colors, being white or pale shades of yellow red green.

According to the concept of the present invention, the naturally-occurring feldspar minerals, which are abundant and relatively cheap, are altered in both chemical and physical characteristics by the removal of a considerable proportion of their alkali metal and aluminum components and the subsequent adsorption of minor amounts of metal salts from aqueous solutions thereof, this combination of treating steps yielding catalyticmaterial of markedly greater potency than the original feldspar or the intermediate material merely after the treatment for the removal of the alkali metals and aluminum.

The general procedure for effecting the treatment of feldspars according to this process is given altered feldspar with a mineral acid, to remove aluminum, calcium oxide, and'calcium chloride, followed by washing. v 4. The digestion of the treated feldspar with solutions of metal salts, principally those of aluminum and the heavy metals (those having a specific gravity of over 4),-to effect the adsorption of small amounts of metal salts onto the more or less activated residue of the feldspar molecules.

5. The final calcination-of the treated material.

I to decompose at least a portion of the adsorbed" salts to release acid radicals and remove water and form acertain amount of metal oxides which apparently act as promoters. v

The following specific example of the preparation of. an altered feldspar'reforming catalyst given to illustrate the general method; 1

Five hundred parts by weight each of final ground orthoclase, lime, and calcium chloride were-intimately mixed andsheated for about 3 hours at a temperature of 1202 F. (650 0.).

The partially fused mix was allowed to cool, pulveri'zed, and washed with about 2 volumes of water. By this Washing step, a large'amount of potassium chloride was extracted, this being re-.

coverable on evaporation pf'the wash water. The

washed material was then digested with about 4 volumes of a per cent hydrochloric acid, after which the remaining insoluble material was washed with water first by decantation-and later by filtering until substantially no' chlorides were present in the washwater. The treated feldspar particles were then added to an aqueous solution consisting of 33.3 parts by weight of hydrated aluminum sulfate (Al2(SO4)a-18H2O) in about 3,000 parts by weight of water, and the suspension was then digested at the boiling point of the solution, using a reflux condenser for a period of about eighteen hours. The particles were again washed by decantation and later by filtering until the wash water contained no sulfates. By this final treating step a small amount-of aluminum salt was apparently adsorbed, probably in the form of a partially hydrolyzed sulfate which was then decomposed to oxide by heating the treated feldsparfor some time at a temperature of about Following the abovet general procedure, it is possible to prepare a considerable number of alternative catalysts in which salts of other metals than aluminum, for example, iron, nickel, cobalt, chromium, molybdenu rfi tungsten, zinc,

. cadmium, copper, etc-., have been adsorbed on themselves in any one cracking reaction or indifferent cracking reactions. Thus the catalysts may vary from' being specific for breaking the carbon-to-carbon bond or cracking to carbon and hydrogen.

It is comprised within the scope of the invention to treat any representative of the feldspar group of minerals first for the removal of a pprtion or substantially all of the alkali metal content, second, for the removal of a portion or substantially all of the aluminum content, and then with diiferent metal salts either single or in combination to further enhance their catalytic.

properties. Practically any soluble .salt may be employed such as a sulfate, chloride, or nitrate although suitable modifications of concentration,

time of treatment with the solution, and final calcination of the treatedfeldspar particles will obviously be necessary. It has been definitely determined that the preliminarily treated feldspars are not zeolytic in character in that the effect of treating with the aqueous solutions of metal salts is not to introduce equivalent metals in place of the removed alkali metals. Analyses of the feldspars after treatment with metal salt solutions indicate that there is no stoichiometr'ic relationship between the amount of alkali metals removed and the amount of metal salts adsorbed, that the metal salts are held by adsorptive and not by the usual valence forces and that their oxides produced by,calcination act as catalyst promoters. The phenomenon of' promoter catalysis is none too well understod at the present time and the present instance is merely cited as one manifestation of the general status.

The present types of catalyst may be employed in any of the ordinary process flows common to commercial reforming plants or special types of plant equipment may be used. The majority of reforming plants in operation at the present time are of the coil and chamber type wherein the oil to be cracked is passed through a continuous tubular element and. brought more'or less quickly up to a temperature at which the rate of the conversion reactions is high enough' for commercial purposes. The heated products are then usually admitted to an enlarged reaction zone in which the. conversion reactions are substantially completed. Following this chamber or zone, the remainder of the elements of the plant are concerned with the fractionationof products with removal of light dgstillates as an overhead, the recycling of intermediate and partially converted cuts and the removal of heavy and readily carbonizable residue. 111 plants of this character a catalyst is most conveniently placed in the reaction chamber as a filler, commonly inthe form of small cylinders or granules of about 6 to 10 mesh diameter. a While it is characteristic of the present process that the catalysts are 'utilizable in the ordinary run of refinery equipment, they also may be employed in special .plant arrangements omitting, for example, the reaction chamber andplacing. the catalyst in the tubes of a continuous series heater. r

The preferred temperature range for the process is from 400 to 750 C. though the range most generally applicable is from 500 to 600 C.-

- In the .majority of instances temperatures of about 500 C. or slightly higher are preferably employed. The preferred pressure is usually "substantially atmospheric or only sufllciently above atmospheric to furnish a head for flow through a chain of apparatus. This factor. however, may be varied depending upon the character of the gasoline subjected to reforming and the degree of reforming required. In some instances a relatively high super-atmospheric pressure may give the best overall'results in. regard to throughput, yield, and quality of product.

Contact times of less than twenty seconds have been-found to be satisfactory, and contact times of three to flve seconds are generally preferred.

The following example is introducedto indicate the general character of the results to be expected when utilizing the present process for reforming low antiknock value gasolinegtho'ugh they are not intended to unduly limit the scope in a general way the effectof the treatment on of the invention. V

-An .orthoclase feldspar was tr'eat'ed for the removal of alkali metals and aluminum and later subjected to treatment with aluminum sulfate solution to permit the adsorption of aluminum sulfate as described in apreceding paragraph.

"The following data is introduced to indicate the chemical composition of the original feldspar.

The first column of figures shows the analysis.

of the original orthoclase without considering any water content. The second column shows thecalculated composition which would correspond to the orthoclase if all alkali metals were removed and replaced by alumina. A third column shows the actual analysis of the material formed as a result of the preliminary treatment for the removal of alkali metals and part of the aluminum followed by. the treatment with aluminum sulfate solution and the final calcining, leaving out the water. content in all instances.

' I Replaced V Constituent Orthoclase' 'orthoclase Treated (calculated) -3? c441 was so. '1 18.2 27.4 1.2 11.0 .0. o- 1.0 0.0 9.0 1.5

Analyses of gases evolved during the calcining step showedoxides of sulfundndicating that the originally adsorbed aluminum sulfate had decomposed to aluminum oxide. 5 A naphtha fraction selected for catalytic reforming had an initialIboilmg P int of 140 (2., a a final boiling point of 225 0., anoctane number of and a sulfur content of 0.30%. ,Thevapors of the naphtha fraction were passed over the catalyst at 500 C., at. atmospheric pressure.

The recovered material had an octane number of and a sulfur content of 0.07%." the yield being 93% of the starting material. The loss was entirely due to gas formation and the gas had the average molecular weight of- 12.1 which indicated. a considerable quantity of hydrogenn The catalyst maintained itsactivity for 'a period of 5 days after which it was restored by merelyoxidizing with air at 500 C.

i The nature of the invention and some ideaof the results to be expected from its use in practice are evident from theforegoing specification andexamples respectively, though neither sectionis expected to be unduly limiting.

I claim as myinvention: 1. A process for increasing the antiknock value of gasoline fractions which comprises sub jecting the same to ieforming conditions in the presence of a modified feldspar "produced by removing from feldspar at least a part of its alkallhous base and aluminum content, adsorbing on the residual portion .of the feldspan'from aqueous solution, a salt of a-metal whose oxide is catalytic and then calcining to convert'said salt to' the catalytic metal oxide supported on the residual portion of the feldspar.

- 2. A process for increasing the antiknock value of gasoline fractions which comprises subjecting the same to reforming conditions in the presence of a catalytic 'metal oxide supported on a feldspar whose alkalinous base and aluminum content has been removed at least in part. 3. A process for increasing the. anti-knock value of gasoline fractions which comprises sub-- jecting'the same .to reforming conditionsin the presence of a modified feldspar produced .by removing from feldspar at least apart of its alkalinous base and aluminum content, treating the residual portion of the feldspar with. an aqueous aluminum salt solution to adsorb aluminumnsalt' .thereon and then calcining to convert the ,ad-

sorbed salt to aluminum oxide supported on the .residualportionof'thefeldspar.

p 4. A' process for increasing the anti-knock value of gasoline fractions which comprises subjectin'g the same to reforming conditionsin the presence of a modified feldspar produced by removing from feldspar at least a partoi' its alkalinous base and aluminum content, treating the residual portion'of the feldspar with an aqueous iron .salt solution to adsorb iron salt thereon and. then calcining to convertthe adsorbed salt to iron oxide supported on the residual portion 'of the feldspar. I

5.= A: process for increasing the anti-knock value of gasoline fractions which comprises sub- Jecting the same to reforming conditions in the presence of a modified feldspar produced by re- F -moving from feldspar at least a part of its alkalinous base and aluminum content, treating the residual portion of the-feldspar with an aqueous nickel saltsolutionto adsorb nickel salt thereon and then calcining to convert the adsorbed salt to nickel oxide supported on the residual portion of the feldspar. r v

6. A process -.for increasing the anti-knock value of gasoline fractions which comprises subjecting the same to reforming conditions in the presence of a modified feldspar produced by removing from-feldspar at least a part of its alkalinous base and aluminum content, treating the residual portion of the feldspar with an aqueous aluminum siufate solutiom to adsorb-aluminum sulfatethereonandthencalcininsto-convertthe 76 7 I adsorbed sulfate to aluminum oxide supported on the residual portion of the feldspar. 1 7. A process for increasing the, anti-knock value of gasoline fractions which comprises subtent has been removed'at least in part.

8. A process for increasing. the anti-knock value of gasoline fractions which comprises subjecting the same to reforming conditions in the 1 presence of an iron oxide supported on a feldspar whose alkalinous base and aluminum content has been removed at least in part.

7 9. A process for increasing the anti-knock value of gasoline fractions which comprises subjecting the same to reforming conditions in the presence of a nickel oxide supported on a feldspar whose alkalinous base and aluminum content has been removed at least in part.

' JACQUE C. MORRELL. 

